In order to observe a microregion of an object, a scanning electron microscope (SEM), a transmission electron microscope (TEM), or the like is used. In general, in such a device, vacuum evacuation of a housing for placing a sample is performed so as to bring a sample atmosphere into a vacuum state, and then, an image of the sample is captured. However, a biochemical sample, a liquid sample, or the like is damaged by the vacuum or the state thereof is changed. On the other hand, the need for observing such a sample with an electron microscope is large, and therefore, an SEM device capable of observing a sample to be observed in an atmospheric pressure, in a desired gas pressure, or in a desired gas species has been strongly demanded.
Therefore, recently, an SEM device capable of placing a sample in an atmospheric pressure, in a desired gas pressure, or in a desired gas species by providing a diaphragm or a micropore which can allow an electron beam to penetrate therethrough between an electron optical system and a sample so as to partition a sample atmosphere and a vacuum in which the electron beam flies has been known. PTL 1 discloses that by using a sample stage provided immediately below a diaphragm, a sample in an atmospheric pressure in a state where the diaphragm and the sample are not in contact with each other is observed with SEM and also the position of the sample is adjusted for the observation.